Journal of Physics D: Applied Physics ( IF 3.1 ) Pub Date : 2021-02-12 , DOI: 10.1088/1361-6463/abde6b Fatma Khammassi 1 , Jose F Lpez 2 , Wajdi Chrif 1 , Aminta Mendoza 2 , Senentxu Lanceros-Mendez 3, 4 , Mohamed Dammak 1 , Daniel Salazar 3
Manganites La0.93K0.07Mn1−x Cu x O3 prepared by the solid state reaction method at high temperature, were studied structurally and magnetically. The unit cell parameters, as well as bond length and the bond angle , were determined from the Rietveld refinement of the x-ray diffraction patterns. The Fourier-transform infrared spectroscopy analysis shows that Cu2+ substitution induces variations in the vibration modes of the MnO6 octahedra. Magnetization vs. temperature at low magnetic field were performed in the range under field coolingand zero field cooling conditions. All the samples exhibited a second-order paramagnetic–ferromagnetic (FM) transition at Curie temperature, , in the range between 199 and 285 K. The inverse susceptibility, exhibits a linear Curie-Weiss (C-W) behavior for , while for , it shows a deviation from the linear behavior predicted by the Heisenberg model. The mentioned deviation of means that a short ferromagnetic state formation is present even for , which were characterized by the experimental effective magnetic moment, A null spontaneous magnetization, above was evaluated for all samples by using the Kouvel-Fisher method. This work evaluates the short-range FM clusters by means of an extension of the C-W approach to the region, i.e., . Finally, the critical coefficient values, and , showed that the 3D Heisenberg model fits adequately the and samples, while the 3D Ising model fits the sample.
中文翻译:
在锰氧化物短程磁性行为的La 0.93 ķ 0.07锰1- X的Cu X ø 3(0.0⩽ X高于居里温度⩽0.09)
在结构和磁性上研究了通过高温固态反应法制备的锰La 0.93 K 0.07 Mn 1- x Cu x O 3。单位晶胞参数,以及键长和键角,是根据X射线衍射图的Rietveld精修确定的。傅立叶变换红外光谱分析表明,Cu 2+取代引起MnO 6八面体振动模式的变化。在低磁场下进行磁化强度与温度的关系 在野外冷却和零野外冷却条件下。所有的样品在居里温度显示出二阶顺磁性铁磁(FM)过渡,在逆易感性199和K. 285之间的范围内,显示出用于线性居里-外斯(CW)的行为,而,它示出了与海森堡模型预测的线性行为的偏差。所提到的偏差的装置,一个短铁磁态的形成是本即使对,将其特征在于所述的实验有效磁矩,空自发磁化,上述使用Kouvel-Fisher方法对所有样品进行了评估。这项工作通过将CW方法扩展到该区域(即)来评估短程FM群集。最后,临界系数值和表示3D Heisenberg模型足够适合和样本,而3D Ising模型适合样本。